Function file_name

pub fn file_name(folder: &Path) -> String

The name of the playlist a folder should hold: the folder’s own name.

Not the album title, which is tempting and wrong twice over: two folders can hold the same title (a rip and a remaster), and a title carries / and : on records that were named by people rather than by filesystems. The folder name is unique where the file goes, is already legal there, and is what the user recognises in a player’s list.